Why does late motherhood increase the chance of Down syndrome in children?

With advances in medical and reproductive technologies, the recent years have witnessed a significant increase in the number of women postponing motherhood until their 30s and 40s. Women who become pregnant after the age of 35 are considered to be of advanced maternal age. This trend is more common among educated women. There are various factors influencing a woman’s decision for delayed pregnancy – availability of safe, effective contraception, late marriages, increasing divorce rates, impaired fertility, career concerns and financial stability seem to be the main reasons. Although most delayed pregnancies result in healthy babies, the risk associated with advanced maternal age should not be ignored.

Risks associated with late pregnancy

Risks associated with pregnancy tend to increase with advancing age, especially after the age 35. With increasing age there is greater likelihood of pre-existing health problems like diabetes, obesity, cardiovascular diseases or kidney disorders. These already present medical conditions can increase the risks associated with the pregnancy. Older mothers have a higher risk of infertility, miscarriages, low birth weight babies, stillbirth, gestational diabetes and other medical conditions. In addition, there is an increased risk of chromosomal abnormalities, especially Down syndrome.

Down syndrome

Down syndrome (DS) is a chromosomal disorder present at birth that changes the physical and intellectual development of the baby. It was first described by Dr. John Langdon Down in 1866. Babies born with DS may have a flat facial profile, slanted eyes, short fingers and other different traits. Down syndrome is the most common cause of mental disability. It is estimated that Down syndrome affects one of every 670 babies born in the United States.

In a normal human being each cell contains 46 chromosomes and these chromosomes are divided into 23 pairs. During conception, one set of 23 chromosomes is inherited from the mother in the egg and the other set of 23 chromosomes comes from father in the sperm. Sometimes due to an error in the division of cells of egg or sperm, a person inherits an extra chromosome from one of his/her parents. Most babies born with Down syndrome have three copies of chromosome 21 instead of two and that’s why it is also known as trisomy. Two other chromosomal abnormalities recognised as mosaicism and translocation is also involved in Down syndrome.

Maternal age and Down syndrome

Late motherhood has been recognized as the primary risk factor associated with fetal Down syndrome. Women are born with the specific quantity of eggs and cannot produce more. These eggs contain the genetic material which they pass on to their offsprings. According to maternal aging theory, with the chronological increase in age, female’s eggs and the genetic material contained within gets older too. Aging genetic material is more likely to have defects occur during cell division that can result in either a lack or an increase in chromosomal material. This phenomenon accounts for the decrease in fertility and increase in chromosomal abnormalities in offsprings of aging women.

Data shows that with the women’s age the risk of having a child affected with Down syndrome increases rapidly. Take it seriously into consideration when planning your pregnancy.

It’s all about health! I have academic background in drugs related Chemical Technology, as well as extensive professional experience in pharma and medical companies. My main area of interest is everyday life medicine. The goal of my articles is to give people informative answers to the questions that bother them, to dispel doubts and some common misbeliefs and also to inspire everyone to keep healthy lifestyle.